Variable displacement compressor

Abstract

A variable displacement compressor which prevents leakage of a refrigerant flowing directly into a suction chamber without passing via a crank chamber at a time of a minimum discharge displacement operation, thus making it possible to prevent an increase of a minimum discharge displacement by increasing a refrigerant pressure in the crank chamber, and in addition, making it possible to prevent insufficient lubrication of sliding portions and the like in the crank chamber.

The invention claimed is: 
     
       1. A variable displacement compressor, which includes:
 a first control valve that controls an opening degree of a pressure supply passage that causes a discharge chamber and a crank chamber to communicate with each other; 
 a check valve that is interposed in the pressure supply passage downstream of the first control valve, and blocks a flow of a refrigerant from a crank chamber side to a first control valve side; 
 a second control valve that controls an opening degree of a pressure release passage that releases a refrigerant pressure in the crank chamber to a suction chamber side in conjunction with the first control valve, receives a refrigerant pressure in a pressure supply passage region downstream of the first control valve and decreases the opening degree of the pressure release passage when the first control valve opens, and receives a refrigerant pressure on the crank chamber side and increases the opening degree of the pressure release passage when the first control valve closes; and 
 a pressure relief passage that relieves a refrigerant pressure in a pressure supply passage region between the first control valve and the check valve to the suction chamber side, 
 in which the variable displacement compressor controls an opening degree of the first control valve to control the refrigerant pressure in the crank chamber, and changes an inclination angle of a swash plate in the crank chamber to vary a discharge displacement, 
 wherein an opening and closing means capable of opening and closing the pressure relief passage is provided. 
 
     
     
       2. The variable displacement compressor according to  claim 1 , wherein the opening and closing means is configured to operate in conjunction with opening and closing operations of the first control valve, to close the pressure relief passage when the first control valve opens, and to open the pressure relief passage when the first control valve closes. 
     
     
       3. The variable displacement compressor according to  claim 2 , wherein the pressure relief passage is configured to relieve the refrigerant pressure in the pressure supply passage region between the first control valve and the check valve to the suction chamber side via an inside of the first control valve, and the opening and closing means is composed integrally with the first control valve and is configured to open and close a pressure relief passage portion in an inside of the first control valve. 
     
     
       4. The variable displacement compressor according to  claim 3 ,
 wherein the first control valve is an electromagnetic control valve that closes to close the pressure supply passage when an electromagnetic coil is magnetized, and opens to open the pressure supply passage when the electromagnetic coil is demagnetized, and 
 the opening and closing means is configured to open the pressure relief passage when the electromagnetic coil of the first control valve is magnetized, and to close the pressure relief passage when the electromagnetic coil of the first control valve is demagnetized. 
 
     
     
       5. The variable displacement compressor according to  claim 4 ,
 wherein the first control valve includes: a valve body that has, on one end side thereof, a first valve portion opening and closing the pressure supply passage, and on other end side thereof, a second valve portion opening and closing the pressure relief passage, and is movably supported in the first control valve; and a restricting portion that, when the electromagnetic coil is demagnetized, receives abutment of the second valve portion, restricts movement of the valve body, and restricts a maximum opening degree of the first valve portion, and 
 the variable displacement compressor has a configuration in which the opening and closing means is composed of the second valve portion of the valve body and the restricting portion, and the pressure relief passage is opened and closed by causing the second valve portion to abut against and separate from the restricting portion. 
 
     
     
       6. The variable displacement compressor according to  claim 5 ,
 wherein the first control valve includes: a valve chamber that has the first valve portion disposed therein and communicates with the discharge chamber; a first pressure chamber that is partitioned from the valve chamber and communicates with the crank chamber; a second pressure chamber that is partitioned from the valve chamber, has the second valve portion disposed therein, and communicates with the suction chamber; and an extended member that is extended from the first valve portion into the first pressure chamber and has an opening portion open to the first pressure chamber, and 
 the pressure relief passage is configured to cause the suction chamber and a region of the pressure supply passage, the region being located between the first control valve and the check valve, to communicate with each other, via the first pressure chamber, the opening portion of the extended member, respective internal spaces of the extended member communicating with the opening portion and the valve body, a communication passage that causes the internal space of the valve body and the second pressure chamber to communicate with each other via the second valve portion, and the second pressure chamber. 
 
     
     
       7. The variable displacement compressor according to  claim 6 , wherein the valve body has a configuration in which other end of a solenoid rod in which one end thereof is coupled to one end of a movable core that moves by electromagnetic force generated by the electromagnetic coil is press-fitted from an end surface side of the second valve portion into the internal space of the valve body via a press-fitting hole formed in the valve body, and enables the valve body to move integrally with the solenoid rod, and the valve body has a configuration in which a groove portion is formed on either one of an outer circumferential surface of the other end of the solenoid rod and an inner circumferential surface of the press-fittting hole, and the groove portion is used as the communication passage.